While I agree with you that there could be many problems with bringing Spider-Man into AoS (such as never being able to mention him on film), I disagree that it would necessarily be a breach of contract to do so. My opinion is that if Sony truly relinquished the live-action TV rights to Marvel (it is still unclear which rights they actually gave up), then Marvel has every right to use the Peter Parker/Spider-Man character in a live-action TV show, no matter who owns the live-action film rights. Of course there could be a clause in the contract about this, but I've never seen it. Have you?
A Marvel-produced "high school Spidey TV show" currently exists, and it is not seen as sabotaging their deal with Sony. Maybe you have seen the contract; have you read that this applies only to a live-action TV version of Spider-Man, but not an animated TV version?
As far as we know, we can't make any claims either way.
I'm relying more on elementary deduction that the contract ensures that Disney cannot utterly screw over Sony. This is under the assumption that Sony's lawyers are not incompetent. It's true, I don't know for sure that they are not though.
But under that assumption, a live action TV show about Peter in High School dating Gwen Stacy fighting Rhino and Electro, as I described earlier, would not only take away much of the anticipation of Amazing Spider-Man 2, but cover story at such a pace that anything ASM2 did would be a retread of the TV show. It would utterly screw over Sony, and so, by elementary deduction, some part of the contract must prevent that from happening. As you can imagine this would not apply to the cartoon high school Peter show, as that would not sate anticipation for live action Spider-Man and the kinds of subtle human stories best told by live action.
So to use Spider-Man on live action TV, as the reports have stated they are fully allowed to, they would have to do so in a way which does not undermine Sony's Spider-Man film... which covers everything about Peter in high school from Gwen to MJ to Harry to Oscorp Conspiracies and so on. If you can't retread any of that... what do you have left? You can put something together with Peter, redesign all his supporting cast and villains so they're still recognizable but clearly separate from the ASM series... but it'd be far
far easier to make that distinction with Miles, and virtually no risk of inadvertently redoing ASM's stories.
Plus, even if my assumption is wrong, it does Disney/Marvel no good to include a TV Spider-Man that takes anything at all away from Sony's series which increases their brand and gives them a cut.
EDIT: Another way to use Peter safely is not to explore his life at all. Just have Spider-Man be a person of interest for SHIELD. Heck, leave his mask on a stuntman and have Drake Bell do the voice. That'd be crazy!